Since humans have 10 fingers, we are partial to a base-10 numbering system. But everyone knows that Martians are partial to hex because they have 8 fingers on each hand. So we can provide a hex to decimal type editor for our users. We’ll express the distance to the target in decimal, but we’ll provide a dropdown hex editor to permit users to select the correct value in base 16. This option is similar to a high-end sports car that provides speed in both miles and kilometers per hour. For this custom type editor, we’ll use a standard Numeric-UpDown control as the user interface for our editor. When the user selects the new Distance property, a drop-down arrow will automatically be displayed, as shown in Figure 5-19.